Background The objective of the current study is to determine to what extent the reduction of Chile’s traffic fatalities and injuries during 2000–2012 was related to the police traffic enforcement increment registered after the introduction of its 2005 traffic law reform.

Methods A unique dataset with assembled information from public institutions and analyses based on ordinary least square and robust random effects models was carried out. Dependent variables were traffic fatality and severe injury rates per population and vehicle fleet. Independent variables were: (1) presence of new national traffic law; (2) police officers per population; (3) number of traffic tickets per police officer; and (4) interaction effect of number of traffic tickets per police officer with traffic law reform. Oil prices, alcohol consumption, proportion of male population 15–24 years old, unemployment, road infrastructure investment, years’ effects and regions’ effects represented control variables.

Results Empirical estimates from instrumental variables suggest that the enactment of the traffic law reform in interaction with number of traffic tickets per police officer is significantly associated with a decrease of 8% in traffic fatalities and 7% in severe injuries. Piecewise regression model results for the 2007–2012 period suggest that police traffic enforcement reduced traffic fatalities by 59% and severe injuries by 37%.

Conclusions Findings suggest that traffic law reforms in order to have an effect on both traffic fatality and injury rates reduction require changes in police enforcement practices. Last, this case also illustrates how the diffusion of successful road safety practices globally promoted by WHO and World Bank can be an important influence for enhancing national road safety practices.